Superfluorescence in semiconductor lasers

An analysis is made of the conditions for the generation of superfluorescence pulses in an inverted medium of electron-hole pairs in a semiconductor. It is shown that strong optical amplification in laser semiconductor amplifiers characterised by αL ≫ 1 leads to suppression of phase re-laxation of the medium during the initial stages of evolution of superfluorescence and to formation of a macroscopic dipole from electron-hole pairs. Cooperative emission of radiation in this system results in generation of a powerful ultrashort pulse of the optical gain, which interacts coherently with the semiconductor medium. It is shown that coherent pulsations of the optical field, observed earlier by the author in Q-switched semiconductor lasers, are the result of superfluorescence and of the coherent interaction between the optical field and the medium.

Superfluorescence in semiconductor lasers

An analysis is made of the conditions for the generation of superfluorescence pulses in an inverted medium of electron-hole pairs in a semiconductor. It is shown that strong optical amplification in laser semiconductor amplifiers characterised by αL ≫ 1 (α is the small-signal gain and L is the amplifier length) leads to suppression of phase relaxation of the medium during the initial stages of evolution of superfluorescence and to formation of a macroscopic dipole from electron - hole pairs. Cooperative emission of radiation in this system results in generation of a powerful ultrashort pulse of the optical gain, which interacts coherently with the semiconductor medium. It is shown that coherent pulsations of the optical field, observed earlier by the author in Q-switched semiconductor lasers, are the result of superfluorescence and of the coherent interaction between the optical field and the medium.

Phase-conjugation broad area twin-contact semiconductor laser

Experimental demonstration of lasing in a broad area twin-contact semiconductor laser which operates as a phase-conjugation (PC) mirror in an external cavity configuration is reported. This allows "self-aligned" and self-pumped spatially nondegenerate four-wave mixing to be achieved without the need for external optical signals. The external cavity laser system is very insensitive to tilt misalignments of the external mirror in the PC regime and exhibits very good mechanical stability. The resonant frequency of the external cavity lies in the GHz range which corresponds to a subnanosecond time response of phase conjugation processes in the semiconductor laser. © 1997 American Institute of Physics.

High power, low-jitter encoded picosecond pulse generation using an rf-locked self-q-switched multicontact GaAs/GaAlAs diode laser

The RF locking of a self-Q-switching diode laser is shown to reduce the jitter of a 2.48 GHz train of 1 W peak power picosecond pulses to less than 300 fs. By using direct modulation of the loss in the Q-switched laser, direct encoding of data has been achieved at rates in excess of 2 Gbit/s.

Narrow line high power picosecond pulse generation in a multicontact distributed feedback laser using modified Q switching

High power bandwidth-limited picosecond pulses with peak powers in excess of 200 mW have been generated using multi-contact distributed feedback laser diodes for the first time. The pulses have widths typically less than 10 ps, time-bandwidth products of as little as 0·24, and can be generated on demand at generator limited repetition rates of up to 140 MHz.

Ultrashort pulse generation in diode lasers

The basic ideas and current state of the art of ultrashort pulse generation by injection lasers are reviewed. All developed techniques, including gain switching, Q-switching, and mode-locking are described and compared. A simple theoretical treatment of a diode laser which emits picosecond light pulses is discussed. Some fundamental limits of the pulse parameters are discussed. Finally, compression of chirped optical pulses by optical fibres and the soliton effect is considered. © 1992 Chapman & Hall.

Generation of picosecond pulses with a repetition frequency of 100 GHz by a multicomponent injection laser

A mode for generating a sequence of spectrally limited pulses with a duration of 2 nsec and a repetition frequency of approximately 100 GHz in AlGaAs/GaAs by an injection heterolaser, which has amplifying and absorbing parts combined in a common resonator, is discussed.

Generation of bandwidth-limited 2 ps pulses with 100 GHz repetition rate from multisegmented injection laser

A new dynamic regime in a multisegmented AlGaAs/GaAs DH injection laser has been realised. Generation of bandwidth-limited 100 GHz repetition rate pulses has been demonstrated. This value is claimed to be the largest ever reported for an ultrashort pulse repetition frequency obtained directly from a laser.

Characteristics of the spectral dynamics of picosecond modulated AlGaAs/GaAs injection lasers

Breakdown of the optical spectrum of a train of picosecond pulses into components with a distance which exceeds kT (200 cm-1 at λ = 955 nm and T = 300 K) is discovered for the first time in an injection laser. The effect may be caused by combined interaction between photons and phonons, with collective excitations in the degraded electron-hole GaAs plasma, and with the stream of drifting carriers in the active medium of the laser.

DIRECT DETECTION OF PICOSECOND PULSES EMITTED BY AN INJECTION LASER WITH ACTIVE MODE LOCKING.

An Agat-SF linear-scan streak image-converter camera was used to record output pulses of 2. 7 psec duration generated by an injection laser with an external dispersive resonator operated in the active mode-locking regime. The duration of the pulses was determined by the reciprocal of the spectral width and the product of the duration and the spectral width was 0. 30.

GENERATION OF PICOSECOND PULSES IN AN INJECTION LASER WITH AN EXTERNAL SELECTIVE RESONATOR.

Pulses of 15 psec duration were generated by an injection laser with an external dispersive resonator operating in the active mode-locking regime. This regime was attained by subjecting the laser diode to a current of high frequency equal to the intermode interval in the external resonator. The duration of the pulses was determined by an autocorrelation method in which the second harmonic was generated in an LiIO//3 crystal.

Mid-infrared Raman-soliton continuum pumped by a nanotube-mode-locked sub-picosecond Tmdoped MOPFA

We demonstrate a mid-infrared Raman-soliton continuum extending from 1.9 to 3 μm in a highly germanium-doped silica-clad fiber, pumped by a nanotube mode-locked thulium-doped fiber system, delivering 12 kW sub-picosecond pulses at 1.95 μm. This simple and robust source of light covers a portion of the atmospheric transmission window. © 2013 Optical Society of America.

Passive and hybrid mode-locking from a monolithic InGaN/GaN laser diode

We report 4ps and 8ps pulse generation from a two-section monolithic InGaN/GaN laser by hybrid and passive mode-locking, respectively. Pulse trains at a repetition rate of 28.6GHz and an emission wavelength of 422nm are generated. © 2013 The Optical Society.

2 to 3 μm Raman-soliton continuum enabled by a nanotube mode-locked Tm-doped MOPFA

We demonstrate a Raman-soliton continuum extending from 2 to 3 μm, in a highly germanium-doped silica-clad fiber, pumped by a nanotube mode-locked thulium-doped fiber system delivering 12 kW sub-picosecond pulses at 1.95 μm. © OSA 2013.